The rehabilitation of completely and partially edentulous patients with dental implants is a scientifically accepted and well documented treatment modality. Currently, titanium and titanium alloys are the materials most often used in implant manufacturing and have become a gold standard for tooth replacement in dental implantology. These materials have attained mainstream use because of their excellent biocompatibility, favorable mechanical properties, and well documented beneficial results. When exposed to air, titanium immediately develops a stable oxide layer, which forms the basis of its biocompatibility. The properties of the oxide layer are of great importance for the biological outcome of the osseointegration of titanium implants.

The principal disadvantage of titanium is its dark grayish color, which often is visible through the peri-implant mucosa, therefore impairing esthetic outcomes in the presence of a thin mucosal biotype. Unfavorable soft tissue conditions or recision of the gingiva may lead to compromised esthetics. This is of great concern when the maxillary incisors are involved. Furthermore, reports suggest that metals are able to induce a nonspecific immunomodulation and autoimmunity. Galvanic side effects after contact with saliva and fluoride are also described. Although allergic reactions to titanium are very rare, cellular sensitization has been demonstrated.

Because of these disadvantages, novel implant technologies that produce ceramic implants are being developed. However, ceramics are known to be sensitive to shear and tensile loading, and surface flaws may lead to early failure. These realities imply a high risk for fracture. In recent years, high-strength zirconia ceramics have become attractive as new materials for dental implants. They are considered to be inert in the body and exhibit minimal ion release compared with metallic implants. Yttrium-stabilized tetragonal zirconia polycrystals appear to offer advantages over aluminum oxide for dental implants because of their higher fracture resilience and higher flexural strength. They have also been used successfully in orthopedic surgery to manufacture ball heads for total hip replacements; this is still the current main application of this biomaterial. Zirconia seems to be a suitable dental implant material because of its toothlike color, mechanical properties, and therefore biocompatibility. Apical bone loss and gingival recession associated with implants often uncover portions of the metal implant, revealing a bluish discoloration of the overlying gingiva. The use of zirconia implants avoids this complication and accedes to the request of many patients for metal-free implants. The material also provides high strength, fracture toughness, and biocompatibility. The inflammatory response and bone resorption induced by ceramic particles are less than those induced by titanium particles, suggesting the biocompatibility of ceramics.

Currently, zirconia dental implant systems are commercially available. The Sigma implant (Sandhause, Incermed, Lausanne, Switzerland), which was developed in 1987, was the first zirconia dental implant system. Additional zirconia implant systems are the CeraRoot system (Oral Iceberg, Barcelona, Spain), the ReImplant system (ReImplant, Hagen, Germany), the White Sky system (Bredent Medical, Senden, Germany), the Goei system (Goei Inc, Akitsu-Hiroshima, Japan), the Konus system (Konus Dental, Bingen, Germany), the Z-systems (Z-systems, Konstanz, Germany), and the Ziterion system (Ziterion, Uffenheim, Germany).

Material composition and surface topography of a biomaterial play a fundamental role in osseointegration. According to Albrektsson et al, the quality of the implant surface is one major factor that influences wound healing at the implantation site and subsequently affects osseointegration. Therefore, various chemical and physical surface modifications have been developed to improve osseous healing. To improve surface properties, 2 main approaches may be used, such as optimizing the micro-roughness (sandblasting, acid-etching) or applying bioactive coatings (calcium phosphate, bisphosphonate, collagen). The clinical use of zirconia dental implants is limited because fabrication of surface modifications is difficult, and smooth implant surfaces are not beneficial for osseointegration because of poor interaction with tissues.

Although zirconia may be used as an implant material by itself, zirconia particles are also used as a coating material of titanium dental implants. A sandblasting process with round zirconia particles may be an alternative surface treatment to enhance the osseointegration of titanium implants.

Many research articles have been written about zirconia dental implants. Thus, the purpose of this review is to summarize research articles conducted on zirconia dental implants, compare them with titanium dental implants, and provide information on zirconia dental implant osseointegration.